Editor's note: This is the last article in a three-part series on evidence-based design.

Evidence-based design is a concept with enormous instinctive appeal for those interested in clinical outcomes, performance improvement, and objective decision making. It is the deliberate attempt to base design decisions on the best available research findings. Evidence-based design for healthcare architecture has been called the natural parallel and analog to evidence-based medicine.

Evidence-Based Practice

Four levels of evidence-based practice were described in the first article in this series (“The Four Levels of Evidence-Based Practice.” HEALTHCARE DESIGN 2003;3[Nov]:18-26). The role of the practitioner can be seen as including: (1) studying the available research and interpretation of the implications for design, (2) hypothesizing the intended results of a design intervention and measuring the outcomes, (3) sharing the results publicly to advance the field, and (4) subjecting the results to peer review and the validity of academic rigor.

An Evidence-Based Design Process

In the second article in this series (“Hypothesis and Measurement: Essential Steps Defining Evidence-Based Design.” HEALTHCARE DESIGN 2004;4[Mar]:43-6), the definition of evidence-based design was proposed as best based on the process, not the result. It is certainly possible for a well-conceived evidence-based project to test important concepts or hypotheses and still yield poor outcomes. Just as the practitioner may work at four levels of increasing rigor, evidence-based projects might also be identified by the level of rigor exercised in the design process.

To review those four levels:

An evidence-based design method or process should support the practitioner's intention to work with these levels of performance. It might include steps similar to the following:

A committed practitioner who follows a consistent process has a good chance of producing a credible evidence-based project. Each practitioner, however, may have an equally valid alternative model that produces good results and meets the standards of rigor required to support the design hypotheses.

Defining an Evidence-Based Project

It is time to develop broadly agreed-upon criteria for measuring the performance of healthcare projects. The ultimate goal would be to develop a rating system for evidence-based designs by which projects of differing scopes in different locations may be consistently compared.

The best evidence-based projects should address serious unanswered questions, rather than simply apply routine or readily available sources as the basis for design. Projects can be of any size, so the extent and complexity of the research effort should be appropriately proportional to the scale of the project. The presence of documented hypotheses associated with the intended outcomes of design interventions is a clear signal that the design is intended to be informed by research.

These hypotheses must be stated in advance, during the design phase, and paired with sound methodology to measure the observed results. Further, the evidence-based process should be applied to concepts or design issues centrally important to the project, rather than tangential elements minimally related to performance measures used by the client. A project exhibiting less rigor might qualify as having used an evidence-based design process but offer insufficient substance to deserve the label of an evidence-based project.

A Modest Proposal

The LEED™ (Leadership in Energy and Environmental Design) Green Building Rating System from the U.S. Green Building Council is an excellent example of a system that rates design projects on the basis of levels of achievement within multiple categories. It might be considered as a model for development of an analogous rating system for evidence-based healthcare projects. If so, what categories would likely be included? The following might serve as examples of possible categories, each with a few suggestions for subcategories that could be measured.

A good model requires a catchy name that has a short and memorable acronym. Consider the Evidence-based Design Assessment & Certification program, or EDAC (e-dak), as a first suggestion.

The best model would include all important and relevant categories, each with reliable measures that had been developed and tested by others. Standard measures with known validity should be used wherever possible. The examples listed above do not pretend to be complete or inclusive. They probably reflect my own unintended biases. They are simply offered as a starting point for a healthy discussion that might develop a full list capable of gaining broad agreement. It would be possible to convene a consensus conference in which such a listing of EDAC categories could be discussed and further developed.

An evidence-based project need not address every category to be considered successful. A successful project that focused on performance improvement, for example, might not have included the features of a healing environment, and vice versa. It would be possible to create an EDAC rating model in which each consensus item resulted in a score, allowing a project to accumulate a point total that matched its characteristics. Such a point total could relate to a minimum threshold for the EDAC label of a registered evidence-based project.

It should be noted that design quality is not among the categories. I currently believe a certification process is not the appropriate way to judge the aesthetic or artistic quality of a building design. On the other hand, the use of an evidence-based process is no excuse for poor design, either. Every design of a healthcare facility should strive for the best quality and value with every dollar spent.

Create a Registry to Increase the Knowledge Base

In addition to the rating scorecard, a project submitted for EDAC review should be required to submit a concise “white paper” that describes the effort. Such a paper would include an introduction that identifies the design idea(s) and the hypotheses on associated outcomes. A section would identify the relevant literature and the specific research on which the current project has based its assumptions. A section on measurement of the outcomes and the methodology used to collect data would precede a section that reports the results obtained. Finally, each paper should include a conclusion that suggests promising avenues for further study on subsequent projects.

A collection of these EDAC papers should be made available to anyone interested. Such a collection would add to the body of knowledge and would rapidly increase the number of concept, methodology, and project examples. Such a source would help illustrate how an evidence-based project is done and invite others to add to the body of work by launching their own research-informed projects.

Certify Individuals Who Demonstrate Expertise

The field is in need of individuals whose education, training, and experience enable them to work as evidence-based practitioners, using appropriate methods and producing successful evidence-based results. These are also the individuals who would best evaluate the registry submissions of others in an EDAC peer-review process. They should be from various fields, including architecture, interior design, engineering, landscape architecture, industrial design, environmental psychology, construction, healthcare management, medicine, nursing, public health, social work, pastoral care, patient advocacy, and numerous other related career paths. Examination-based certification is a way to develop a group of these individuals. Anyone interested in the process, and willing to study and pass the EDAC examination, should be encouraged to become EDAC certified.

Universities interested in evidence-based design might develop course structures in which graduates or continuing education participants might qualify for EDAC certification. The courses would teach the theory and methods of evidence-based design for healthcare and would provide a detailed introduction to the broad range of research findings currently available. Participants would learn how to identify solid research and how to use critical thinking to determine the design implications of research relevant to their own specific design problem. Organizations such as The Center for Health Design, the AIA, ASID, IIDA, ASHRAE, or ASHE also could offer courses to practitioners leading to certification. A robust system of EDAC certification would require serious continuing education to stay current with a rapidly evolving body of knowledge and emerging research.

Recognize Exemplary Projects

Some projects will rise above the level of most and will deserve some special recognition for their achievement. The LEED model offers Certified, Silver, Gold, and Platinum awards for projects whose scores achieve certain minimum numbers of points. It would be possible for the EDAC model to develop levels of superior performance measured by the rating system and to reward the teams with some sort of well-deserved public recognition.

An Invitation to Convene

The Center for Health Design is prepared to take leadership in this important area and facilitate the development of the EDAC certification process. The Center is a multidisciplinary group that touches most groups that might have an interest in the topic, and is therefore uniquely qualified to act as a central and neutral player in this effort. Supportive and collaborative efforts from other organizations would be welcome.

To kick off the effort to develop the EDAC certification system, The Center will convene interested participants during the HEALTHCARE DESIGN .04 conference, November 7-9 in Houston, to look at the development of this model. A presentation at the conference will be devoted to exploring evidence-based design for this purpose. The Center for Health Design is seeking volunteers to participate on an EDAC task force to guide the evolving process. If you are interested, please e-mail Debra Levin at dlevin@healthdesign.org to volunteer.


The first article in this series attempted to define evidence-based practice. The second attempted to define an evidence-based design process and recognized the difficulties associated with identifying an evidence-based project. This article completes the series by proposing a specific way in which The Center for Health Design might sponsor an assessment system to clarify the identification of evidence-based projects. This should lead to wider understanding and to the celebration of projects that have met the new standards.

Clients, researchers, or design professionals would submit projects to be recognized as evidence-based, and the submission itself would add to the growing body of knowledge. Projects would be rated on a broadly consensus-based scale and would be reviewed by individuals who have become certified in the area of evidence-based design. Exemplary projects would be celebrated through an awards program based on superior levels of scoring within the rating system.

Such a model would encourage individuals to develop their understanding of evidence-based design and become EDAC certified. Recognition of evidence-based projects would be possible through EDAC registration, and superior performances could be publicly celebrated through an EDAC awards program. If the EDAC model is a success, there should be many more individuals qualified to do the work, more projects recognized for their reported results, and more publicity for the accomplishments of the most successful projects. This should make an important positive contribution to the exciting future of healthcare design. HD


  • A level-one process must have a significant number of design decisions specifically attributable to interpretation of the implications of research findings, which could be derived from a wide variety of credible sources.

  • A level-two process would require advance documentation of multiple design hypotheses and linking the research findings to intended outcomes, with appropriate measures used to gauge the success or failure of the design in use.

  • Level three is achieved when the results are reported impartially in public, through writing or speaking. To avoid bias, or the appearance of bias, it would be best to have an impartial third party review the data-collection methods and provide an independent report of the results.

  • Finally, a level-four process requires that the research methods, data collection, and reporting are subjected to the rigor of peer review and meet academic standards for validity.


  1. Set the design goals and objectives.

  2. Identify the key design issues suited to evidence-based design.

  3. Research the key topics and benchmark the field for relevant examples.

  4. Use critical thinking to explore the complicated implications of the research.

  5. Hypothesize the intended result(s) of the design intervention(s).

  6. Select appropriate measures to determine the strategy's success or failure.

  7. Properly construct the building or physical environment.

  8. Carefully measure the results.

  9. Report unbiased findings from an independent source.

  10. Subject the findings to the scrutiny of a peer-review process.


Overall Organizational Performance:

  • Financial and economic measures (including margin and average cost per patient day)

  • Clinical measures (including average length of stay [ALOS], stress measures, medication errors, nosocomial infection rate, fall rate, and mortality)

  • Satisfaction measures (including patient satisfaction, family satisfaction, staff satisfaction, physician satisfaction, market share, and community perception).

Social and Cultural Interventions:

  • Environment supportive of family and social connections

  • Environment supportive of the staff

  • Philosophy of care

  • Organizational culture

Commitment to Safety:

  • Aspects of patient safety

  • Safety for the staff

  • Continuous improvement model

Healing Environments:

  • Stress reduction

  • Access to nature

  • Attention to the senses

  • Wayfinding

  • Positive distractions

Performance Improvement:

  • Efficiency

  • Systems initiatives

Technology Usage/Leverage:

  • Medical technologies

  • Computer technologies

  • Labor-saving technologies

Sustainable Design (consider adopting the LEED certification criteria):

  • Energy consumption

  • Material selection

  • Water conservation

  • Site planning